Wiring device



April 1953 v. L. CARISSIMI 2,831,085

WIRING DEVICE Filed Jan. 3', 1956 INVENTOR Vincent L.Corlssimi (MKM'I-MATTORNEY United States Patent WIRING DEVICE Vincent L. Carissimi,Fairfield, Comm, assignor to The Bryant Electric Company, Bridgeport,Conm, a corporation ol: Connecticut Application January 3, 1956, SerialNo. 556,954

4 Claims. (Cl. 200-113) My invention relates to a wiring device and,more particularly, to an infinitely variable position electrical switchfor controlling the energization of an electrical heating element.

As is well known, it is the present practice to provide electricalswitches for controlling electrical heating elements which have acycling movable circuit making and breaking element for controlling theheat dissipation of the heating element. Such switches are provided withan infinite number of positions up to and including the high or full onposition so that the heat dissipation may be infinitely varied. The useof the cycling element is, however, undesirable when the switch is inthe full oni position due to the fact that such cycling ele ment, aloneor in series with a heater element, is a cur rent carrying member whichat the full on position causes a high heat dissipation within theswitch. In addition, the use of a cycling member in the full on positionrequires some positive means to hold the cycling member in the full onposition. Heretofore, it has been common practice to mechanically engagethe cycling member for such holding which has resulted in stressing thecycling member. Such mechanical stress accompanied with the reducedallowable stress at elevated temperatures has resulted in overstressingthe cycling member.

Accordingly, one object of my invention is to provide a shunt brush fora cycling control device.

Another object of my invention is to provide a cycling control devicehaving an infinite number of positions, within limits, the cyclingmember of which is shunted at oneposition of the device. I I

These and other objects of my invention .will become more apparent uponthe following detailed description of a preferred embodiment of myinvention when taken in' conjunction with the attached drawings, inwhich:

Figure'l is a sectional view of a switch constructed in accordance withvthe'principles of my invention taken. along theline lI of Fig. 2; and IFig. 2 is a cross section view of the switch shown in Fig. 1 taken alongthe line 11-11 thereof. I

It willbe noted that the switch shown in Figs. land 2 is substantiallyidentical to the switch shown in the copending application. Serial No.556,953, filed concurrently herewith by O. L. Taylor and C. M. Smithentitled. Wiring Device and which has been assigned to the same assigneeas this invention. For a more complete descrip-- tion of theconstruction of many portions of the switch. described herein,theabove-identified application should be consulted. The switch of myconstruction differs in. that a shunt brush is used to shunt the cyclingelement in the fullon position of the handle, as is more fully describedherein. A

The switch shown in the drawings comprises a rectangular one-piececup-shaped housing 2 having a base 13, and'integrallongitudinally'extending laterally spaced. side walls'sand 9which areconnected at their ends by 2,831,085 Patented Apr. 15, 1958 means oflaterally extending end walls 12. Housing 2 may be formed from anysuitable insulating material and is preferably formed from a moldedplastic material which may readily be formed as hereinafter described.As shown, a pair of laterally spaced terminals 4 and 6 are locatedinwardly adjacent one end wall 12 of housing 2 and a similar terminal 10is located inwardly adjacent the opposite end wall 12. Terminals 4, 6and 10 may be made from any suitable electrical conducting material,such as an alloy of copper, and are each provided with integralconnector engaging portions which extend through a slot (not shown) inbase 13 of housing 2 and outwardly from the outer side of base 13 ofhousing 2 so that wiring connections may readily be made theretoexternally of the housing 2. Such out.- warclly extending connectorengaging portions are shown only for the terminals 4 and 6 in Fig. 2;however, terminal 10 is similar thereto. The portions of terminals 4, 6and 10 which extend inwardly of housing 2 are larger than the slotsthrough which the connector engaging portions extend so that terminals4, 6 and 10 may readily be located in place by merely inserting theconnector engaging portions through the slots in the base 13 andthereafter wedging a portion of the connector engaging portion into firmengagement with the outer surface of base 13. It will also be noted thatthe inwardly extending portion of terminal 10 is located onapproximately the longitudinal center line of housing 2 and extendslongitudinally between the end wall 12. T erminals 4 and 6 extendlongitudinally between end walls 12; however, they are spaced laterallyon opposite sides of the longitudinal center line of housing 2, withterminal 4 being offset toward side wall 8 of housing 2 and terminal 6being offset toward side wall 9.

Terminals 4 and 6 are adapted to be electrically con nected to terminal10 by means of generally longitudinally extending brushes 14 and 16,respectively. One end of each brush 14 and 16 is formed to extendadjacent the inwardly located portion of terminal 10 so that brushes 14and 16 may be electrically and mechanically secured thereto in anysuitable manner such as by means of rivets, not shown. Brushes 14 and 16are formed from any suitable electrical conducting material, such as analloy of copper which has sufiicient resiliency to bias the oppositefree ends of brushes l4 and 16 into engagement with terminals 4- and 6,respectively. The free end of brush to is provided with a laterallyextending arcuate surface 15 for engaging the surface of terminal 6facing side wall 9. Brush 16 is utilized to control a pilot light, andaccordingly, it does not carry any substantial amount of current so thatsuch contact engagement is satisfactory. Brush 14 is, however, a linecurrent-carrying member, and in order to minimize arcing damage whenbrush 14 engages the surface ofterminal 4 facing side wall 9, theopposed portions of terminal 4 and brush 14 are provided with areresistant contacts 17 and 19, respectively, which may be formed from anysuitable are resistant material, such as silver or an alloy thereof.Contacts 19 and 17 may be secured to the brush 14 and terminal 4,respectively, in any suitable manner, such as by being riveted thereto.

It will be noted that brush 16 is formed so that the portion adjacentterminal 10 extends sharply toward side wall 9 and thereafter is formedto provide a straight portion 20 which extends toward the terminal 6. Asterminal 10 is located on approximately the longitudinal center line ofhousing 2, it is obvious that brush 16 is offset towards side wall 9.Straight portion 20 of brush 16 extends to each side of the lateralcenter line of housing 2. and is provided approximately centrallythereon with an integral inwardly extending projection 22. The portionof brush 14. intermediate its fixed and free ends is generally U-shapedwith its arms extending outwardly from each other and with its bightportion 24 being located approximately parallel to and inwardly adjacentto the straight portion 26 of brush 16. Bight portion 24 is also offsetfrom the longitudinal center line of housing 2 toward side wall 9 ofhousing 2.

Brushes 14 and 16 are operated by means of a formed cam 26 which isrotatably supported within the housing 2' and is formed of any suitableinsulating material, such as a molded plastic material which may readilybe pro vided with the necessary structure as hereinafter described. Asshown, cam 26 is provided with a central axially extending circularopening 28 through which an elongated operating shaft 30 extends. Shaft30 may be formed from any suitable material having sufficient structuralstrength, such as steel. in order to rotatably support the inner end ofshaft 30 within the housing 2, the inner surface of the base 13 isprovided with a circular recess 32 in which the circular inner end ofshaft 30 is rotatably received. If desired, a boss 34 may be providedwhich extends inwardly from base 13 of housing 2 for engaging the innerend of cam 26 to support the cam 26 above the inner surface of base 13.In such event recess 32 also extends through boss 34.

The entire open side of housing 2 is enclosed by means of a cover 36which may be formed of any suitable material, such as steel, and whichis secured to the open side or" housing 2 in any suitable manner, suchas by means of projections at the sides thereof, not shown, which aredeformable to engage cam surfaces on the sides 8 and 9 of the housing 2.Cover 36 is provided with an approximately central opening 21 which isin alignment with the excess 32 and through which the outer end of shaft36 extends and is freely supported thereby. if desired, the outer end ofshaft may be provided with suitable means, such as a slot 38, forsecuring a handle, not shown, thereto whereby the shaft 30 may readilybe rotated in order to accomplish the purposes as hereinafter described.

Although cam 26 may be secured to shaft 30 in numerous satisfactory waysto obtain rotation of the cam 26, as shown, the opening 28 is enlargedradially at its outer end and shaft 39 is also enlarged radially so thatthe inner end of the enlarged portion of shaft 36 is closely receivedtherein. The enlarged portion of shaft 30 is of a non-circular crosssection in order that a catch 42 may be placed thereon and benon-rotatably supported by the shaft 30 so that rotation of shaft 30causes a corresponding rotation of catch 42. As shown, catch 42 isprovided with a pair of inwardly extending lugs 48 which are closelyreceived in inwardly extending recesses 50, only two of which are shown,which extend inwardly from the outer surface of cam 26. Thus, rotationof shaft 30 causes lugs 48 of catch 42 to engage the sides of recesses50 to cause a corresponding rotation of cam 26. In order to locate catch42 axially along shaft 30, a suitable stop member 44 may be secured toshaft 30 for engaging the inwardly facing surface of catch 42. Further,a spring member 46 may be located on shaft 30 for biasing the catch 42into engagement with the stop member 44 which is located between theinwardly facing surface of cover 36 and the outwardly facing surface ofcatch 42.

As best shown in Fig. l, the inner end of cam 26 is circular in formexcept for a narrow projection 52 extending radially outwardlytherefrom. The inner end of cam 26 is of a size so that it may be freelyrotated without engaging the brush 14 adjacent thereto. Projection 52 isof a size that upon such rotation it engages the bight portion 24 ofbrush 14 to force brush 14 towards side wall 9 and separate the contacts17 and 19. Such movement of brush 14 also causes the bight portion 24 toengage the inwardly facing end of projection 22 and force the brush 16out of engagement with the terminal 6. Inasmuch as the brush 14 movestoward the terminal 6, housing 2 is preferably provided with an upwardlyextending integral barrier 51 which extends longitudinally between theinner portions of terminals 4 and 6 whereby the free end of brush 14 isprevented from engaging the terminal 6.

As shown, an elongated generally longitudinally extending resilientbimetal element 54 is located inwardly adjacent side wall 8 with the endlaterally spaced from terminal 10 being secured to a terminal 56 whichis similar in construction to terminal 10. Terminal 56 is secured tobase 13 in a similar manner to terminal 10 so that the inner portionextends slightly angularly from the adjacent end wall 12 upwardly towardside wall 8. Eimetal element 54 may be formed from any suitable pair ofdissimilar materials having different coefiicients of thermal expansionsuch as are generally available commercially in the well known manner.One end of bimetal 54 is fixedly secured to the inner portion ofterminal 56 in any suitable manner, such as by rivets 57,

only one of which is shown. A contact 58 similar to the contacts 17 and19, previously described, is secured to the opposite movable end ofbimetal 54 in any suitable manner such as by being riveted thereto.

An elongated longitudinally extending resilient bimetal element 60,which is substantially identical to the bimetal 54, is located inwardlyadjacent side wall 9 so that it extends generally longitudinally of sidewall 9. As shown, the end of bimetal 60 laterally spaced from terminal56 is pivotally secured to the housing 2, and the opposite movable endof bimetal 60 is laterally spaced from the movable end of bimetal 54. Across link 62 of any suitable material, such as spring steel, extendslaterally between the movable ends of bimetal elements 54 and 60 and islocated inwardly adjacent the end wall 12 between the inner surface ofend wall 12 and the adjacent terminals 4 and 6. Cross link 62 ispivotally secured to both bimetals 54 and 60 in any suitable manner,such as by forming the ends of the cross link 62 to engage formed slots(not shown) in the movable ends of bitnctals 54 and 60 into which theformed ends of cross link 62 may be inserted. Thus, movement of eitherbimetal S4 or 60 in either direction causes a corresponding movement inthe opposite bimetal 54 or 60 due to the cross connection of cross link62.

Still another terminal 64, similar to terminals 4, 6, 10 and 56previously described, is secured to base 13 of housing 2 in the samemanner as previously described. Terminal 64 is located laterally betweenthe terminals 10 and 56 and further inwardly toward the center ofhousing 2. As shown, a composite bimetal element 66 extends inwardlyfrom and longitudinally adjacent bimetal 54 and is secured to theinwardly extending portion of terminal 64 in any suitable manner, suchas by rivets 59. Composite bimetal 66 comprises a light bimetal section68 which is secured to the terminal 64 and a heavier bimetal section 70which is secured to the bimetal section 68 in any suitable manner, suchas by being spot welded thereto. As shown, bimetal section 70 is similarto the bimetals 54 and 60. previously described. While the bimetalsection 68 is also formed of two dissimilar materials, in the samemanner as bimetal 54 previously described, it is of substantially lessthickness than bimetals 54, 60 and 70. A contact 72 similar to thecontacts 17 and 19, previously described, is secured to the free end ofbimetal section 70 in any suitable manner, such as by riveting, so as to'be cooperable with the contact 58 on bimetal 54. Although not shown,the portion of bimetal section 68 between terminal 64 and bimetalsection 70 has been reduced in width to obtain a more rapid movementinto and out of engage ment with contact 58 on bimetal 54 as describedin the above identified copending application.

As has been indicated, bimetal 60 is pivotally supported at one of itsends. As shown, housing 2 is provided with an integral projection 71which extends inwardly at the intersection of side wall 9 with end wall12 adjacent the terminals and 56. Projection 72 is provided with asurface facing terminal 10in which a generally V- shaped notch 74 isprovided so that projection 72 may function as a pivot support. Anelongated rigid cam follower 76, which may be formed from any suitablematerial having sufficient structural strength, such as steel, isprovided, which extends generally longitudinally within housing 2adjacent the side wall 9. One end of cam follower 76 is formed toprovide a pair of spaced laterally outwardly extending projections 78,the free ends. of which are freely received within the V-shaped notch 74in projection 72, so that camffollower 76 is pivotally supportedtherein. In order that projections 78 are retained within the notch 74,biasing means comprising a generally omega-shaped spring 80 is providedwhich may be formed from any suitable spring material, such as steel. Asshown, a projection 82 is provided on cam follower 76 which extendslaterally therefrom toward the side wall 8 and which is located, forconvenience'in fabrication, between the projections 78.

Housing 2 is also provided with an integral support 84 between thepivotally supported end of cam follower 76 and terminal 10 which extendsinwardly from the base 13 and which has a notch 85 therein facing thepivotally supported end of cam follower 76. With such construction, theopposed arms of spring 80 may be inserted within the notch 85 and theintersection of the projection 82 with the cam follower 76,respectively, so that the arms of spring 80 are forced toward each otherwhen the cam follower 76 is inserted within housing 2. Movement of camfollower 76 toward side wall 9 causes the central portion of spring 80to be compressed to bias the cam follower 76 toward side wall 8. It, ofcourse, will be appreciated that'in order to provide an initial bias oncam follower 76 the armsof spring 80 are initially stressed toward eachother when inserted in position as described.

It will particularly be noted that the opposed bimetals 54 and 60 arelocated adjacent the inner surface of base 13 and that the cam follower76 is spaced outwardly from the inner. surface of base 13 so as to bemovable transversely across the outeredge of the bimetal 60 heretoforedescribed. In view of such location of cam follower 76, it is providedwith an integral portion, not shown, adjacent its pivotally supportedend which extends toward the base 13 so that the end of bimetal 60spaced from the cross link 62 may be secured thereto in any suitablemanner, such as by rivets, not shown. Thus, movement of cam follower 76will cause a movement of thepbimetal 60 which, in turn, as previouslystated, will cause a movement of bimetal 54. 7

Although not shown, cross link 62 is provided with an upwardly extendingprojection approximately centrally thereof, one end of which isengageable with the free end of cam follower 76. Engagement of camfollower 76 and the projection provides a positive off position for theswitch. As shown, the central portion of cam follower 76 is offsettowards side wall 9 with its free end being formed to extend sharplytoward the side wall 8. The central portion of cam follower 76 extendsadjacent an irregularly formed cam portion 94 which is an integralportion of cam 26. Engagement between cam portion 94 and cam follower 76is obtained by means of a screw 95 threadedly engaging the centralportion of cam follower 76 and which extends therethrough. It will benoted that the end of screw 95 facing side wall 9 is provided with aslot whereby the relative position between cam follower 76 and camportion 94 may be varied. In' order to facilitate such adjustment anopening, not shown, is provided in the side wall 9 in alignment with thescrew 95.

The construction of the switch heretofore described provides bimetal 54which cycles into and out of electrical and mechanical engagement withbimetal 56 as is more 6 fully described in the above identifiedcopending application. The above identified copending application alsoparticularly describes and shows the fact that the terminal 56 iselectrically connected to a source of suitableelectrical energy so thatcurrent flows from terminal 56 through bimetal54, contact 58, contact72, bimetal 66 and terminal 64 which in turn is connected by means of asuitable electrical conductor to one end of an electrical heatingelement. Thus, the cycling of the bimetal 54 controls the electricalenergy input to the heating element, which due to the cycling of bimetal54 varies depending upon the position of bimetal 54. With thisconstruction the turning of cam plate 26 to the full on position causescontacts 58 and 72 to remain'in engagement with each other constantly.As the current flows through the bimetal. 54 and bimetal 66, a largeamount of heat energy will be dissipated within the switch with theresultant loss of electrical energy at the full on position. In order toprevent such heat dissipation, I have provided a shunt brush which maybe formed of any suitable electrical conducting material havingsufiicient resiliency, such as an alloy of copper, which is movable toelectrically connect terminal 56 to terminal 64 when the cam 26 is inthe full on position.

Shunt brush 100 is generally U-shaped with one arm being longer than theother. As shown, the short arm 102 of shunt brush 100 is connected toterminal 56 in any suitable manner, such as by utilizing the rivets 57previously described. The long arm 104 of shunt brush 100 extendsgenerally longitudinally within housing 2 between the bimetal 66 and thelongitudinal center line of housing 2. A suitable electrical contact106, which is similar to the contacts 17 and 19 previously described, issecured to arm 104 at approximately its midpoint in any suitable manner,such as by being riveted thereto. Contact 106 is cooperable withterminal 64, which cooperation may be provided by utilizing one of therivets 59 as previously described. Accordingly, as shown, the rivet 59in lateral alignment with contact 106 may be fabricated from a silveralloy or be silver plated to minimize the arcing damage resulting fromits engagement with contact 106.

As shown, the free end of arm 104 of shunt brush 100 extendslongitudinally inwardly of housing 2 so as to be spaced outwardly fromthe path of projection 52 on the inner end of cam 26. The free end ofarm 104 is also formed so as to extend below the cam portion 94 so as tobe located between the cam portion 94 and the inner surface of base 13.In order to provide means for activating arm 104 of shunt brush 100, cam26 between its inner end carrying projection 52 and the cam portion 94is provided with an integral radial outwardly extending projection 110which is of a radial length greater than projection 52 and less thanthat portion of cam portion 94 in alignment therewith. Thus, uponrotation of cam 26, projection 110 engages the free end of arm 104 toforce arm 104 toward the bimetal 66 so that the contact 106 mountedthereon engages the cooperable rivet 59 on the terminal 64, as shown indotted lines in Fig. 1. In accordance with my invention, shunt brush 100is provided with sufficient cross-sectional area and is of asufliciently high conductivity material so that such engagement ofcontact 106 with rivet 59 on terminal 64 provides a low resistanceelectrical path between the terminal 56 and the terminal 64. Such a lowresistance path between these terminals shunts the current so that thebimetals 54 and 66 are not heated to any substantial degree. If desiredin order to provided a smooth engagement between the projection 110 andthe free end of arm 104, an offset portion 112 may be provided at theextreme end of arm 104. Also if desired, arm 104 may be indented towardsthe arm 102 at approximately its midpoint in order to increase thedistance between the separate contacts 106 and 59. Thus, it will benoted that with my invention I have provided a low resistance auxiliarycontact system which is separately controllable by the cam 26 so as toshunt the cycling contact assembly for the full on position of the cam26. It will particularly be noted that such a control has been achievedby using the same terminals of the circuit as are used in the cyclingportion of the switch.

Having described a preferred embodiment of my invention in accordancewith the patent statutes, it is desired that my invention be not limitedto the specific construction illustrated, inasmuch as it will beapparent to those skilled in the art that many modifications thereof maybe made without departing from the broad spirit and scope of myinvention. Accordingly, it is desired that my invention be interpretedas broadly as possible and that it be limited only as required by theprior art.

I claim as my invention:

1. A wiring device comprising an insulating support, a pair of spacedterminals secured to said support, elongated bimetal elements securedadjacent one end to said terminals, respectively, so as to extendoutwardly therefrom in substantially the same direction, operating meansmovably mounted on said support and including one cam portion foractuating means connected to one of said bimetal elements to cause theother end of said one bimetal element to engage the other end of saidother bimetal element, at least one of said terminals being adapted tobe connected to a source of electrical energy so that a current flowsthrough said engaged bimetal elements, a resilient conducting membersecured to one of said terminals and having an extending end locatedadjacent the other of said terminals, and said operating means havinganother earn position engageable with said resilient member uponrotation of said operating means to one position to move said extendingportion of said resilient means into engagement with said other terminalwhereby said bimetal elements are shunted.

2. A wiring device comprising an insulating support, a pair of spacedterminals secured to said support, an elongated resilient bimetalelement secured to one of said terminals so as to extend outwardlytherefrom, operating means movably mounted on said support having a camsurface thereon, follower means movably mounted on said supportengageable with said cam surface so as to be movable upon movement ofsaid operating means, said follower means being connected to saidbimetal element to move the extending portion of said bimetal elementinto engagement with a contact connected with the other of saidterminals so that various pressures are exerted therebetween, aresilient member secured to one of said terminals and having anextending portion located adjacent the other of said terminals,

a second cam surface on said operating means engageable with saidresilient member upon movement of said operating means to one positionto move said extending portion of said resilient member into engagementwith said last-mentioned other of said terminals Whereby said bimetalelement is shunted.

3. A wiring device comprising, a support of insulating material, spacedterminals mounted on said support, an elongated bimetal element havingone end mounted on one of said terminals and a contact mounted adjacentthe other end thereof, a cooperating contact connected with the other ofsaid terminals, manually operable means movably mounted on' saidsupport, means including a resilient member operated by said manualmeans to move said other end of the bimetal element in a direction toclose said contacts selectively under various contact pressuresdependent on the amount of movement of said manual means, a movablecontact member connected to one of said terminals for movement into andout of engagement with a part connected to the other of said terminals,and said movable contact having a part directly operable by said manualmeans at a position thereofof maximum pressure on said firstmentionedcontacts.

4. A Wiring device comprising, a support of insulating material, spacedterminals mounted on said support, an elongated bimetal element havingone end mounted on one of said terminals and a contact mounted adjacentthe other end thereof, a cooperating contact connected with the other ofsaid terminals, manually operable means movably mountedon said support,means including a resilient bimetal member operated by said manual meansto move said other end of the bimetal element in a direction to closesaid contacts selectively under various contact pressures dependent onthe amount of movement of said manual means, said bimetal elementsarranged to deflect in opposing senses in response to a giventemperature change to compensate for ambient temperature changes, amovable contact member connected to one of said terminals for movementinto and out of engagement with a part connected to the other of saidterminals, and said movable contact having a part directly operable bysaid manual means at a position thereof of maximum pressure on saidfirstmentioned contacts.

References Cited in the file of this patent UNITED STATES PATENTS1,634,431 Meyers July 5, 1927 2,182,048 Elmer Dec. 5, 1939 2,280,960 LeeApr. 28, 1942

